Mutli-purpose contact lens care compositions

ABSTRACT

Multi-purpose solutions for contact lens care provide substantial lens wearer/user comfort and/or acceptability. Such solutions include an aqueous liquid medium; an antimicrobial component, preferably a biguanide polymer present in an amount of less than about 5 ppm; a surfactant component, preferably a poly(oxyethylene)-poly(oxypropylene) block copolymer surfactant, in an effective amount; a phosphate buffer component in an effective amount; a viscosity inducing component, preferably selected from cellulosic derivatives, in an effective amount; and a tonicity component in an effective amount. Such solutions have substantial performance, comfort and acceptability benefits, which, ultimately, lead to ocular health advantages and avoidance of problems caused by contact lens wear.

BACKGROUND OF THE INVENTION

The present invention relates to compositions for treating, for example,disinfecting, cleaning, soaking, conditioning and wetting contactlenses. More particularly, the invention relates to multi-purposesolutions useful in treating contact lenses, for example, fordisinfecting contact lenses, for removing deposit material from contactlenses, for soaking, conditioning and/or wetting contact lenses and thelike, which provide substantial comfort and acceptability benefits tothe users of such solutions.

Contact lenses need to be periodically treated, for example,disinfected, cleaned, soaked and the like, on a regular basis because ofthe tendency for a variety of ocular and environmental contaminants,microbes and other materials to accumulate on the lenses and/or the needto provide the lenses in suitable condition for safe and comfortablewear. User compliance, that is users treating contact lenses on aregular and consistent basis, is important in order to promote ocularhealth and to avoid problems associated with contact lens wear. Usercompliance is enhanced when the treatment solution employed provideshigh degrees of lens wearer/user comfort and acceptability. Therefore,it would be advantageous to provide compositions for treating contactlenses which provide such comfort and/or are accepted by contact lenswearers/users of such compositions.

Fu U.S. Pat. No. 4,323,467 discloses an aqueous composition combining apoly(oxyethylene)-poly(oxypropylene) substituted ethylenediaminesurfactant, a germicidal agent, a viscosity builder, a tonicity agent, asequestering agent and water for treating rigid contact lenses. Thispatent discloses a germicide, such as thimerosal and/or benzalkoniumchloride, in a concentration of 0.0005%-0.05%. The Fu patent does notdisclose the use of any specific buffer. Although the compositions ofthe Fu patent have multiple utilities, there is a potential for eyediscomfort and/or irritation, for example, because of the relativelyhigh concentrations of germicide and the apparent lack of pH control.

British Pat. No. 1,432,345 discloses a contact lens disinfectingcomposition including an ophthalmically acceptable biguanide in a totalamount of from 0.0005% to 0.05% by weight. This British patent disclosesthat the solution preferably has a pH of from 5 to 8 and employs aphosphate buffer. The patent also discloses employing additionalbactericides, thickening agents and non-ionic surfactants, as well asdisodium EDTA in concentrations of at least 0.1%. Although thesecompositions are effective as contact lens disinfectants, they do pose arisk of eye discomfort and/or irritation, for example, because of therelatively high concentrations of biguanide and EDTA employed.

Ogunbiyi et al U.S. Pat. No. 4,758,595 discloses an aqueous solution ofa biguanide in an amount of 0.000001 to 0.0003% weight percent incombination with a borate buffer system, EDTA, and one or moresurfactants. This U.S. Patent additionally states that conventionalbuffers, other than the borate buffer, can be used but only inconjunction with increased amounts of biguanide. Thus, the generalconclusion of this U.S. Patent is that if reduced amounts of biguanideare to be used, a borate buffer is essential. Although such compositionsare useful, the potential for ocular discomfort and irritation in arelatively large percentage of the total population still exists, forexample, because of the requirement that a borate buffer be employed.

There continues to be a need to provide new contact lens treatmentsystems, for example, multi-purpose solutions, that effect the desiredtreatment or treatments of the lens and, at the same time, providesubstantial, preferably enhanced, lens wearer/user comfort andacceptability.

SUMMARY OF THE INVENTION

New compositions for treating contact lenses have been discovered. Thepresent compositions, that is multi-purpose aqueous solutions, includeantimicrobial components, preferably reduced concentrations ofantimicrobial components, in combination with phosphate buffers andviscosity inducing components to provide the desired antimicrobialactivity and performance effectiveness and, importantly, substantial,preferably enhanced, lens wearer/user comfort and acceptabilitybenefits. These compositions are surprising and unexpected in view ofthe above-noted prior art which employs relatively large concentrationsof antimicrobial components and/or buffering systems other thanphosphate buffering systems and/or does not employ viscosity inducingcomponents. In addition, the inclusion of one or more other componentsin the present compositions is effective in providing additionalbeneficial properties to the compositions, and preferably providefurther lens wearer/user comfort and acceptability benefits. The presentcompositions have a multitude of applications, for example, asdisinfecting, cleaning, soaking, wetting and conditioning compositions,for contact lens care, while providing substantial lens wearer/usercomfort and acceptability. The present compositions preferably increaseuser compliance, that is promote regular and consistent contact lenscare, and, ultimately, lead to or facilitate better ocular health.

In one embodiment of the present invention, multi-purpose solutions forcontact lens care are provided. Such solutions comprise an aqueousliquid medium; an antimicrobial component in an amount effective todisinfect a contact lens contacted with the solution; a surfactant in anamount effective in cleaning a contact lens contacted with the solution;a phosphate buffer component in an amount effective in maintaining thepH of the solution within a physiologically acceptable range; aviscosity inducing component present in an effective amount; and atonicity component in an amount effective in providing the desiredtonicity to the solution.

The antimicrobial component may be any suitable, preferablyophthalmically acceptable, material effective to disinfect a contactlens contacted with the present solutions. Preferably, the antimicrobialcomponent is selected from biguanides, biguanides polymers, saltsthereof and mixtures thereof, and is present in an amount in the rangeof about 0.1 ppm to about 3 ppm or less than 5 ppm (w/v). The preferredrelatively reduced concentration of the antimicrobial component has beenfound to be very effective, in the present compositions, in disinfectingcontact lenses contacted with the compositions, while at the same timepromoting lens wearer/user comfort and acceptability.

Any suitable, preferably ophthalmically acceptable, surfactant componentwhich is effective in cleaning contact lenses may be employed. Thesurfactant component preferably is non-ionic and, more preferably, isselected from poly(oxyethylene)-poly(oxypropylene) block copolymers andmixtures thereof.

Any suitable, preferably ophthalmically acceptable, viscosity inducingor thickening agent may be included in the present compositions. Theviscosity inducing component preferably is selected from cellulosicderivatives and mixtures thereof and is present in an amount in therange of about 0.05% to about 0.5% (w/v). Without wishing to limit theinvention to any particular theory of operation, it is believed that thepresence of a viscosity inducing component at least assists in providingthe lens wearer/user comfort and acceptability benefits of the presentinvention, which promote regular and consistent contact lens care andultimately lead to or facilitate better ocular health. The presentcombinations of components, for example, including such viscosityinducing components, are effective in providing the degree of lenswearer/user comfort and acceptability benefits described herein.

Although any suitable, preferably ophthalmically acceptable, tonicitycomponent may be employed, a very useful tonicity component is acombination of sodium chloride and potassium chloride.

The present compositions preferably include an effective amount of achelating component. Any suitable, preferably ophthalmically acceptable,chelating component may be included in the present compositions,although ethylenediaminetetraacetic acid (EDTA), salts thereof andmixtures thereof are particularly effective. More preferably, thepresent compositions include chelating components in effective amountsless than about 0.05% (w/v) and still more preferably 0.02% (w/v) orless. Such reduced amounts of chelating component in the presentcompositions remain effective in providing the desired chelating and/orsequestering functions while, at the same time, are better tolerated inthe eye, thereby reducing the risk of user discomfort and/or ocularirritation.

Various combinations of two or more of the above-noted components may beused in providing at least one of the benefits described herein.Therefore, each and every such combination is included within the scopeof the present invention.

These and other aspects of the present invention are apparent in thefollowing detailed description, examples and claims.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to multi-purpose solutions useful fortreating, for example, disinfecting, cleaning, soaking, rinsing,wetting, conditioning and the like, contact lenses. Any contact lenses,for example, conventional hard contact lenses, rigid gas permeablecontact lenses and soft, hydrophilic or hydrogel, contact lenses, can betreated in accordance with the present invention.

In one embodiment, the present compositions comprise a liquid aqueousmedium; an antimicrobial component in the liquid aqueous medium in anamount effective to disinfect a contact lens contacted with thecomposition; a surfactant, preferably a non-ionic surfactant, componentin an amount effective in cleaning a contact lens contacted with thecomposition; a phosphate buffer component in an amount effective inmaintaining the pH of the composition within a physiologicallyacceptable range; an effective amount of a viscosity inducing component;and an effective amount of a tonicity component. The presentcompositions preferably include an effective amount of a chelating orsequestering component, more preferably in a range of less than 0.05%(w/v). Each of the components, in the concentration employed, includedin the solutions and the formulated solutions of the present inventionpreferably are ophthalmically acceptable. In addition, each of thecomponents, in the concentration employed, included in the presentsolutions preferably is soluble in the liquid aqueous medium.

A solution or component thereof is "ophthalmically acceptable" when itis compatible with ocular tissue, that is, it does not cause significantor undue detrimental effects when brought into contact with oculartissue. Preferably, each component of the present compositions is alsocompatible with the other components of the present compositions. Thepresent compositions are more preferably substantially ophthalmicallyoptimized. An ophthalmically optimized composition is one which, withinthe constraints of component chemistry, minimizes ocular response, orconversely delivers ophthalmic benefit to the lens wearing eye.

The presently useful antimicrobial components include chemicals whichderive their antimicrobial activity through a chemical or physiochemicalinteraction with microbes or microorganisms, such as those contaminatinga contact lens. Suitable antimicrobial components are those generallyemployed in ophthalmic applications and include, but are not limited to,quaternary ammonium salts used in ophthalmic applications such aspoly[dimethylimino-2-butene-1,4-diyl] chloride,alpha-[4-tris(2-hydroxyethyl) ammonium]-dichloride (chemical registrynumber 75345-27-6, available under the trademark Polyquaternium 1® fromOnyx Corporation), benzalkonium halides, and biguanides, such as saltsof alexidine, alexidine-free base, salts of chlorhexidine, hexamethylenebiguanides and their polymers, and salts thereof, antimicrobialpolypeptides, chlorine dioxide precursors, and the like and mixturesthereof. Generally, the hexamethylene biguanide polymers (PHMB), alsoreferred to as polyaminopropyl biguanide (PAPB), have molecular weightsof up to about 100,000. Such compounds are known and are disclosed inOgunbiyi et al U.S. Pat. No. 4,758,595, the disclosure of which ishereby incorporated in its entirety by reference herein.

The antimicrobial components useful in the present invention preferablyare present in the liquid aqueous medium in concentrations in the rangeof about 0.00001% to about 2% (w/v).

More preferably, the antimicrobial component is present in the liquidaqueous medium at an ophthalmically acceptable or safe concentrationsuch that the user can remove the disinfected lens from the liquidaqueous medium and thereafter directly place the lens in the eye of safeand comfortable wear.

The antimicrobial components suitable for inclusion in the presentinvention include chlorine dioxide precursors. Specific examples ofchlorine dioxide precursors include stabilized chlorine dioxide (SCD),metal chlorites, such as alkali metal and alkaline earth metalchlorites, and the like and mixtures thereof. Technical grade sodiumchlorite is a very useful chlorine dioxide precursor. Chlorinedioxide-containing complexes such as complexes of chlorine dioxide withcarbonate, chlorine dioxide with bicarbonate and mixtures thereof arealso included as chlorine dioxide precursors. The exact chemicalcomposition of many chlorine dioxide precursors, for example, SCD andthe chlorine dioxide complexes, is not completely understood. Themanufacture or production of certain chlorine dioxide precursors isdescribed in McNicholas U.S. Pat. No. 3,278,447, which is incorporatedin its entirety herein by reference. Specific examples of useful SCDproducts include that sold under the trademark Dura Klor by Rio LindaChemical Company, Inc., and that sold under the trademark AnthiumDioxide by International Dioxide, Inc.

If a chlorine dioxide precursor in included in the present compositions,it preferably is present in an effective contact lens disinfectingamount. Such effective disinfecting concentrations preferably are in therange of about 0.002 to about 0.06% (w/v) of the present compositions.Such chlorine dioxide precursors may be used in combination with otherantimicrobial components, such as biguanides, biguanide polymers, saltsthereof and mixtures thereof.

In the event that chlorine dioxide precursors are employed asantimicrobial components, the compositions preferably have an osmolalityof at least about 200 mOsmol/kg and are buffered to maintain the pHwithin an acceptable physiological range, for example, a range of about6 to about 10.

In one embodiment, the antimicrobial component is non-oxidative. It hasbeen found that reduced amounts of non-oxidative antimicrobialcomponents, for example, in a range of about 0.1 ppm to about 3 ppm orless than 5 ppm (w/v), in the present compositions are effective indisinfecting contact lenses and reduce the risk of such antimicrobialcomponents causing ocular discomfort and/or irritation. Such reducedconcentration of antimicrobial component is very useful when theantimicrobial component employed is selected from biguanides, biguanidepolymers, salts thereof and mixtures thereof.

When a contact lens is desired to be disinfected by the presentcompositions, an amount of the antimicrobial component effective todisinfect the lens is used. Preferably, such an effective amount of theantimicrobial component reduces the microbial burden or load on thecontact lens by one log order in three hours. More preferably, aneffective amount of the disinfectant reduces the microbial load by onelog order in one hour.

The phosphate buffer component is present in an amount effective tomaintain the pH of the composition or solution in the desired range, forexample, in a physiologically acceptable range of about 4 or about 5 orabout 6 to about 8 or about 9 or about 10. In particular, the solutionpreferably has a pH in the range of about 6 to about 8. The phosphatebuffer component preferably includes one or more phosphate buffers, forexample, combinations of monobasic phosphates, dibasic phosphates andthe like. Particularly useful phosphate buffers are those selected fromphosphate salts of alkali and/or alkaline earth metals. Examples ofsuitable phosphate buffers include one or more of sodium dibasicphosphate (Na₂ HPO₄), sodium monobasic phosphate (NaH₂ PO₄) andpotassium monobasic phosphate (KH₂ PO₄). The present buffer componentsfrequently are used in amounts in a range of about 0.01% or about 0.02%to about 0.5% (w/v), calculated as phosphate ion.

The present compositions preferably further comprise effective amountsof one or more additional components, such as a detergent or surfactantcomponent; a viscosity inducing or thickening component; a chelating orsequestering component; a tonicity component; and the like and mixturesthereof. The additional component or components may be selected frommaterials which are known to be useful in contact lens care compositionsand are included in amounts effective to provide the desired effect orbenefit. When an additional component is included, it is preferablycompatible under typical use and storage conditions with the othercomponents of the composition. For instance, the aforesaid additionalcomponent or components preferably are substantially stable in thepresence of the antimicrobial and buffer components described herein.

A surfactant component preferably is present in an amount effective incleaning, that is to at least facilitate removing, and preferablyeffective to remove, debris or deposit material from, a contact lenscontacted with the surfactant-containing solution. Exemplary surfactantcomponents include, but are not limited to, nonionic surfactants, forexample, polysorbates (such as polysorbate 20-Trademark Tween 20), 4-(1,1, 3, 3-tetramethylbutyl) phenol/poly(oxyethylene) polymers (such as thepolymer sold under the trademark Tyloxapol),poly(oxyethylene)-poly(oxypropylene) block copolymers, glycolic estersof fatty acids and the like, and mixtures thereof.

The surfactant component preferably is nonionic, and more preferably isselected from poly(oxyethylene)-poly(oxypropylene) block copolymers andmixtures thereof. Such surfactant components can be obtainedcommercially from the BASF Corporation under the trademark Pluronic®.Such block copolymers can be generally described aspolyoxyethylene/polyoxypropylene condensation polymers terminated inprimary hydroxyl groups. They may be synthesized by first creating ahydrophobe of desired molecular weight by the controlled addition ofpropylene oxide to the two hydroxyl groups of propylene glycol. In thesecond step of the synthesis, ethylene oxide is added to sandwich thishydrophobe between hydrophile groups.

In accordance with a more preferred embodiment of the invention, suchblock copolymers having molecular weights in the range of about 2500 to13,000 daltons are suitable, with a molecular weight range of about 6000to about 12,000 daltons being still more preferred. Specific examples ofsurfactants which are satisfactory include: poloxamer 108, poloxamer188, poloxamer 237, poloxamer 238, poloxamer 288 and poloxamer 407.Particularly good results are obtained poloxamer 237.

The amount of surfactant component, if any, present varies over a widerange depending on a number of factors, for example, the specificsurfactant or surfactants being used, the other components in thecomposition and the like. Often the amount of surfactant is in the rangeof about 0.005% or about 0.01% to about 0.1% or about 0.5% or about 0.8%(w/v).

The viscosity inducing components employed in the present solutionspreferably are effective at low or reduced concentrations, arecompatible with the other components of the present solutions and arenonionic. Such viscosity inducing components are effective to enhanceand/or prolong the cleaning and wetting activity of the surfactantcomponent and/or condition the lens surface rendering it morehydrophilic (less lipophilic) and/or to act as a demulcent on the eye.Increasing the solution viscosity provides a film on the lens which mayfacilitate comfortable wearing of the treated contact lens. Theviscosity inducing component may also act to cushion the impact on theeye surface during insertion and serves also to alleviate eyeirritation.

Suitable viscosity inducing components include, but are not limited to,water soluble natural gums, cellulose-derived polymers and the like.Useful natural gums include guar gum, gum tragacanth and the like.Useful cellulose-derived viscosity inducing components includecellulose-derived polymers, such as hydroxypropyl cellulose,hydroxypropylmethyl cellulose, carboxymethyl cellulose, methylcellulose, hydroxyethyl cellulose and the like. More preferably, theviscosity inducing agent is selected from cellulose derivatives(polymers) and mixtures thereof.

A very useful viscosity inducing component is hydroxypropylmethylcellulose (HPMC).

The viscosity inducing component is used in an amount effective toincrease the viscosity of the solution, preferably to a viscosity in therange of about 1.5 to about 30, or even as high as about 750, cps at 25°C., preferably as determined by USP test method No. 911 (USP 23, 1995).To achieve this range of viscosity increase, an amount of viscosityinducing component of about 0.01% to about 5% (w/v) preferably isemployed, with amounts of about 0.05% to about 0.5% being morepreferred.

A chelating or sequestering component preferably is included in anamount effective to enhance the effectiveness of the antimicrobialcomponent and/or to complex with metal ions to provide more effectivecleaning of the contact lens.

A wide range of organic acids, amines or compounds which include an acidgroup and an amine function are capable of acting as chelatingcomponents in the present compositions. For example, nitrilotriaceticacid, diethylenetriaminepentacetic acid,hydroxyethylethylene-diaminetriacetic acid, 1,2-diaminocyclohexanetetraacetic acid, hydroxyethylaminodiacetic acid,ethylenediamine-tetraacetic acid and its salts, polyphosphates, citricacid and its salts, tartaric acid and its salts, and the like andmixtures thereof, are useful as chelating components.Ethylenediaminetetraacetic acid (EDTA) and its alkali metal salts, arepreferred, with disodium salt of EDTA, also known as disodium edetate,being particularly preferred.

The chelating component preferably is present in an effective amount,for example, in a range of about 0.01% and about 1% (w/v) of thesolution.

In a very useful embodiment, particularly when the chelating componentis EDTA, salts thereof and mixtures thereof, a reduced amount isemployed, for example, in the range of less than about 0.05% (w/v) oreven about 0.02% (w/v) or less. Such reduced amounts of chelatingcomponent have been found to be effective in the present compositionswhile, at the same time, providing for reduced discomfort and/or ocularirritation.

The liquid aqueous medium used is selected to have no substantialdeleterious effect on the lens being treated, or on the wearer of thetreated lens. The liquid medium is constituted to permit, and evenfacilitate, the lens treatment or treatments by the presentcompositions. The liquid aqueous medium advantageously has an osmolalityin the range of at least about 200 mOsmol/kg for example, about 300 orabout 350 to about 400 mOsmol/kg. The liquid aqueous medium morepreferably is substantially isotonic or hypertonic (for example,slightly hypertonic) and/or is ophthalmically acceptable.

The liquid aqueous medium preferably includes an effective amount of atonicity component to provide the liquid medium with the desiredtonicity. Such tonicity components may be present in the liquid aqueousmedium and/or may be introduced into the liquid aqueous medium. Amongthe suitable tonicity adjusting components that may be employed arethose conventionally used in contact lens care products, such as variousinorganic salts. Sodium chloride and/or potassium chloride and the likeare very useful tonicity components. The amount of tonicity componentincluded is effective to provide the desired degree of tonicity to thesolution. Such amount may, for example, be in the range of about 0.4% toabout 1.5% (w/v). If a combination of sodium chloride and potassiumchloride is employed, it is preferred that the weight ratio of sodiumchloride to potassium chloride be in the range of about 3 to about 6 orabout 8.

Methods for treating a contact lens using the herein describedcompositions are included within the scope of the invention. Suchmethods comprise contacting a contact lens with such a composition atconditions effective to provide the desired treatment to the contactlens.

The contacting temperature is preferred to be in the range of about 0°C. to about 100° C., and more preferably in the range of about 10° C. toabout 60° C. and still more preferably in the range of about 15° C. toabout 30° C. Contacting at or about ambient temperature is veryconvenient and useful. The contacting preferably occurs at or aboutatmospheric pressure. The contacting preferably occurs for a time in therange of about 5 minutes or about 1 hour to about 12 hours or more.

The contact lens can be contacted with the liquid aqueous medium byimmersing the lens in the medium. During at least a portion of thecontacting, the liquid medium containing the contact lens can beagitated, for example, by shaking the container containing the liquidaqueous medium and contact lens, to at least facilitate removal ofdeposit material from the lens. After such contacting step, the contactlens may be manually rubbed to remove further deposit material from thelens. The cleaning method can also include rinsing the lenssubstantially free of the liquid aqueous medium prior to returning thelens to a wearer's eye.

The following non-limiting examples illustrate certain aspects of thepresent invention.

EXAMPLE 1

A solution is prepared by blending together the following components:

    ______________________________________                                        PHMB                   1 ppm (w/v)                                              (polyhexamethylene biguanide)                                                 Disodium EDTA 0.02% (w/v)                                                     Poloxamer 237 0.05% (w/v)                                                     (poly(oxyethylene)-poly                                                       (oxypropylene) block                                                          copolymer)                                                                    Sodium Phosphate                                                              Dibasic (heptahydrate) 0.12% (w/v)                                            Sodium Phosphate                                                              Monobasic (monohydrate) 0.01% (w/v)                                           HPMC (Hydroxypropylmethyl                                                     Cellulose) 0.15% (w/v)                                                        Sodium Chloride 0.79% (w/v)                                                   Potassium Chloride 0.14% (w/v)                                                Water (USP) Q.S. 100%                                                       ______________________________________                                    

Approximately three (3) ml of this solution is introduced into a lensvial containing a lipid, oily deposit laden, hydrophilic or soft contactlens. The contact lens is maintained in this solution at roomtemperature for at least about four (4) hours. This treatment iseffective to disinfect the contact lens. In addition, it is found that asubstantial portion of the deposits previously present on the lens hasbeen removed. This demonstrates that this solution has substantialpassive contact lens cleaning ability. Passive cleaning refers to thecleaning which occurs during soaking of a contact lens, withoutmechanical or enzymatic enhancement.

After this time, the lens is removed from the solution and is placed inthe lens wearer's eye for safe and comfortable wear. Alternately, afterthe lens is removed from the solution, it is rinsed with anotherquantity of this solution and the rinsed lens is then placed in the lenswearer's eye for safe and comfortable wear.

EXAMPLE 2

Example 1 is repeated except that the lens is rubbed and rinsed with adifferent quantity of the solution prior to being placed in the lensvial. After at least about four (4) hours, the lens is removed from thesolution. The lens is then placed in the lens wearer's eye for safe andcomfortable wear.

EXAMPLE 3

The solution of Example 1 is used as a long-term soaking medium for ahydrophilic contact lens. Thus, approximately three (3) ml of thissolution is placed in a vial and a contact lens is maintained in thesolution at room temperature for about sixty (60) hours. After thissoaking period, the lens is removed from the solution and placed in thelens wearer's eye for safe and comfortable wear. Alternately, after thelens is removed from the solution, it is rinsed with another quantity ofthis solution and the rinsed lens is then placed in the lens wearer'seye for safe and comfortable wear.

EXAMPLE 4

A hydrophilic contact lens is ready for wear. In order to facilitatesuch wearing, one or two drops of the solution of Example 1 is placed onthe lens immediately prior to placing the lens in the lens wearer's eye.The wearing of this lens is comfortable and safe.

EXAMPLE 5

A lens wearer wearing a contact lens applies one or two drops of thesolution of Example 1 in the eye wearing the lens. This effects are-wetting of the lens and provides for comfortable and safe lens wear.

EXAMPLE 6

A series of tests are conducted to evaluate the comfort, safety andacceptability of the solution prepared in accordance with Example 1compared to two other solutions.

The first of these other solutions, referred to hereinafter asComposition A, is sold under the trademark ReNut by Bausch & Lomb andincludes 0.5 ppm PHMB, a poly(oxyethylene)-poly(oxypropylene)substituted ethylenediamine surfactant, a borate buffer system, 0.1%disodium EDTA, and sodium chloride as a tonicity agent.

The second of these other solutions, referred to hereinafter asComposition B, is similar to the composition of Example 1 except thatComposition B included 0.6% (w/v) tromethamine, and neither of thephosphates.

Each of these compositions is tested to evaluate its comfort, safety andacceptability for the care of hydrogel (hydrophilic) contact lenses wornon a daily basis among subjects previously adapted to at least onecommercially available multi-purpose solution.

The study is a randomized, double-masked, three-way cross over study.The study is broken down into a series of three (3) one (1) monthtreatment periods. Each of the compositions is used on a daily basis forcleaning, rinsing after cleaning, disinfection, and rinsing prior tolens application, as needed. Because each treatment period is only one(1) month in duration, no enzymatic cleaner is used in this study.

The subjects are evaluated at day zero (baseline), day seven (7) and daythirty (30) for each of the three (3) treatment periods. The primarycomfort and acceptability variables are lens wearing comfort and end ofstudy product preference. The primary safety variable is slit lampexamination findings.

123 subjects are enrolled. 116 (94.3%) complete PreferenceQuestionnaires for Treatment Period 2. 118 (95.9%) complete PreferenceQuestionnaires for Treatment Period 3.

The results of this study are summarized as follows. The slit lampexaminations indicate that each of the compositions tested is acceptablysafe. The comfort and acceptability results included in this summary arebased on subjective answers to selected questions (at the end ofTreatment Periods 2 and 3).

Further tabulations are made based on subjective answers to the selectedquestions noted above, as well as to other questions included in thePreference Questionnaires. These tabulations are made using answers fromthe Preference Questionnaires for Treatment Period 3.

Results of these further tabulations are as follows:

    ______________________________________                                                    Respondents                                                          Preferring Respondents                                                        Example 1 Preferring No                                                       Composition Composition A Pre- P                                             Preference Question % % ference Value                                       ______________________________________                                          Overall preference 65 28  7 0.02                                              In-the-hand preference 56 27 17 0.02                                          In-the-eye preference 63 27 11 0.02                                           Comfort in-the-eye 60 25 15 0.02                                              Amount of time for 47 21 32 0.02                                              lenses to settle                                                              in the eye                                                                    Keeping lenses 55 28 17 0.02                                                  moist in eyes                                                                 Keeping lenses 57 28 15 0.02                                                  lubricated in eyes                                                            Soothing in eyes 57 27 16 0.02                                              ______________________________________                                                    Respondents                                                          Preferring Respondents                                                        Composition B Preferring No                                                   Composition Composition A Pre- P                                             Preference Question % % ference Value                                       ______________________________________                                          Overall preference 55 40  5 0.18                                              In-the-hand preference 51 31 18 0.08                                          In-the-eye preference 60 34 6 0.02                                            Comfort in-the-eye 36 34 10 0.06                                              Amount of time for 44 31 25 0.26                                              lenses to settle                                                              in the eye                                                                    Keeping lenses 47 34 19 0.26                                                  moist in eyes                                                                 Keeping lenses 47 32 21 0.18                                                  lubricated in eyes                                                            Soothing in eyes 57 32 10 0.02                                              ______________________________________                                         *BASED ON A PVALUE OF 0.02, THESE RESULTS ARE SIGNIFICANT AT A 95% LEVEL      OF CONFIDENCE                                                            

These results indicate a clear preference of the composition of Example1 over Composition A; and an overall preference of the composition ofExample 1 over Composition B.

These results are indeed surprising since Composition A is acommercially available multi-purpose solution. Possible reasons for thepreference of the Example 1 composition relative to Composition Ainclude one or more of the presence of HPMC, the presence of apoly(oxyethylene)-poly(oxypropylene) block copolymer surfactant, thepresence of the phosphate buffer, and/or the presence of a reducedamount of EDTA.

The present compositions provide a very beneficial and advantageouscombination of performance efficacy and lens wearer/user comfort andacceptability. In the context of contact lens care solutions, lenswearer/user comfort and acceptability are very important, for example,to promote regular and effective treating of contact lenses. Suchtreating of contact lenses ultimately promotes ocular health and reducesthe frequency of problems caused by wearing contact lenses. Thus, lenswearer/user comfort and acceptability are of substantial importance andbenefit in a contact lens care product, in particular in the presentcompositions which exhibit substantial, even enhanced, lens wearer/usercomfort and acceptability.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

What is claimed is:
 1. A multi-purpose solution for contact lens carecomprising:an aqueous liquid medium; an antimicrobial componentcomprising an agent selected from the group consisting ofpolyhexamethylene biguanides and salts thereof and mixtures thereof, inan amount in a range of about 0.1 ppm to 1 ppm; a surfactant consistingof a poly(oxyethylene)-poly(oxypropylene) block copolymer in an amounteffective in cleaning a contact lens contacted with said solution; and aphosphate buffer component in an amount effective in maintaining the pHof said solution within a physiologically acceptable range.
 2. Themultpurpose solution of claim 1 further comprising a viscosity inducingcomponent selected from the group consisting of cellulosic derivativesand mixtures thereof in an effective amount in a range of about 0.05% toabout 0.5% (w/v).
 3. The multipurpose solution of claim 2 wherein saidviscosity inducing component is hydroxypropylmethyl cellulose.
 4. Themultipurpose solution of claim 1 further comprising:a viscosity inducingcomponent selected from the group consisting of cellulosic derivativesand mixtures thereof in an effective amount in a range of about 0.05% toabout 0.5% (w/v); a chelating component in an effective amount of lessthan 0.05%(w/v); and a tonicity component in an amount effective inproviding the desired tonicity to said solution.
 5. The multi-purposesolution of claim 1 wherein said surfactant is present in an amount inthe range of about 0.01% to about 0.8%(w/v).
 6. The multi-purposesolution of claim 4 wherein said phosphate buffer component includes acombination of sodium hydrogen phosphate and sodium dihydrogenphosphate.
 7. The multi-purpose solution of claim 4 wherein saidphosphate buffer component is present in an amount in a range of about0.01% to about 0.5%(w/v).
 8. The multi-purpose solution of claim 4wherein said viscosity inducing component is hydroxypropylmethylcellulose.
 9. The multi-purpose solution of claim 4 wherein saidtonicity component includes a combination of sodium chloride andpotassium chloride and is present in a range of about 0.4% to about1.5%(w/v).
 10. The multi-purpose solution of claim 4 wherein saidchelating component is selected from the group consisting ofethylenediaminetetraacetic acid, alkali metal salts ofethylenediaminetetraacetic acid and mixtures thereof.